Preheat the oven to 140°C (275°F), gas mark 1.
Heat half the oil in a frying pan over a medium heat and brown the lamb. Remove and place in a large ovenproof dish and add the sweet potato wedges.
Using the rest of the oil, fry the onion until softened. Add the tomatoes and their juice and cook for 4-5 minutes.
Add the tomato purée, cumin, oregano, honey and chicken stock. Season with salt and pepper and pour this over the lamb and sweet potatoes.
Cover with foil and bake in the preheated oven for 1 hour.
Add the soya beans, cover and cook for another 20 minutes. Stir in the parsley 10 minutes before serving. Remove the foil and stir in the lemon juice.
Serve with rice, mashed potatoes or flatbreads for mopping up the juices.